msc {
	hscale = "1.5";
	phy,bts,pcu,bsc;

	---  		[ label = "...Voice call 1 ends" ];
	bts => bsc	[ label = "Release Ind" ];
	bsc => bts	[ label = "RSL RF Channel Release (TCH/H)" ];
	bts => phy	[ label = "L1 chan Deactivate SAPIs" ];
	bts -> bsc	[ label = "RSL RF Channel Release Ack (TCH/H)" ];
	---  		[ label = "BSC notices: one chan still in use"];

	---  		[ label = "...Voice call 2 ends" ];
	bts => bsc	[ label = "Release Ind" ];
	bsc => bts	[ label = "RSL RF Channel Release (TCH/H)" ];
	bts => phy	[ label = "L1 chan Deactivate SAPIs" ];
	bts -> bsc	[ label = "RSL RF Channel Release Ack (TCH/H)" ];

	phy box bsc	[ label = "If all channels on TS are released, PDCH Activation" ];
	bsc => bts	[ label = "RSL Channel Activation (PDCH)" ];
	bts -> bsc	[ label = "RSL Channel Activation Ack (PDCH) (unconditionally)" ];
	---  		[ label = "BTS notices: chan still connected as TCH/H, reconnect" ];
	bts => phy	[ label = "L1 chan Disconnect TCH/H" ];
	phy -> bts	[ label = "L1 chan Disconnect confirm" ];
	bts => phy	[ label = "L1 chan Connect PDTCH" ];
	phy -> bts	[ label = "L1 chan Connect confirm" ];
	---  		[ label = "chan reconnect as PDTCH complete" ];
	bts => pcu	[ label = "Info Ind (Activate)" ];
	pcu => bts	[ label = "chan Activate request" ];
	bts => phy	[ label = "L1 chan Activate PDTCH SAPIs" ];
	phy -> bts	[ label = "L1 chan Activate SAPIs confirm" ];
}